s = "123456789"
a1 = 2
a2 = 4


# 结果为: "12789"


def pop_str(s, a1, a2=0):
    s1 = s[:a1]  # 切片获取前面字符串
    s2 = s[a1 + a2:]  # 切片获取后面字符串
    return s1 + s2


print(pop_str(s, 20, 4))
